Al-si-fe casting alloys

ABSTRACT

New aluminum casting (foundry) alloys are disclosed. The new aluminum casting alloys may include from 6.0 to 11.5 wt. % Si, from 0.30 to 0.80 wt. % Fe, optionally from 0.07 to 0.20 wt. % of X, wherein X is selected from the group consisting of Mg, Mo, Zr, and combinations thereof, and optionally 100-500 ppm Sr, the balance being aluminum and unavoidable impurities. The new aluminum casting alloys may be high-pressure die cast into complex shapes. The new aluminum casting alloys may be useful, for instance, in heat sink/antenna applications.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent Application No. PCT/US2021/034577, filed May 27, 2021, which claims the benefit of U.S. Provisional Patent Application No. 63/032,973 filed Jun. 1, 2020, entitled “AL-SI-FE CASTING ALLOYS,” each of which is incorporated herein by reference in its entirety.

BACKGROUND

Aluminum alloys are useful in a variety of applications. Aluminum casting (foundry) alloys, for instance, are used in dozen of industries, including, for instance, the automotive and consumer electronics industries.

SUMMARY OF THE DISCLOSURE

Broadly, the present disclosure relates to new aluminum casting (foundry) alloys and associated products. The new aluminum casting alloys generally comprise (and in some instances consist of or consist essentially of) from 6.0 to 11.5 wt. % Si, from 0.30 to 0.80 wt. % Fe, optionally from 0.07 to 0.20 wt. % of X, wherein X is selected from the group consisting of Mg, Mo, Zr, and combinations thereof, and optionally 100-500 ppm Sr, the balance being aluminum and unavoidable impurities. The new aluminum casting alloys may realize an improve combination of properties, such as an improved combination of two or more of strength, thermal conductivity, corrosion resistance, fluidity, and die soldering resistance.

i. Composition

As noted above, the new aluminum casting alloys generally include from 6.0 to 11.5 wt. % Si. In one embodiment, a new aluminum casting alloy includes at least 7.0 wt. % Si. In another embodiment, a new aluminum casting alloy includes at least 8.0 wt. % Si. In yet another embodiment, a new aluminum casting alloy includes at least 8.5 wt. % Si. In another embodiment, a new aluminum casting alloy includes at least 9.0 wt. % Si. In yet another embodiment, a new aluminum casting alloy includes at least 9.5 wt. % Si. In one embodiment, a new aluminum casting alloy includes not greater than 11.0 wt. % Si. In another embodiment, a new aluminum casting alloy includes not greater than 10.5 wt. % Si.

As noted above, the new aluminum casting alloys generally include from 0.30 to 0.80 wt. % Fe. In one embodiment, a new aluminum casting alloy includes at least 0.35 wt. % Fe. In another embodiment, a new aluminum casting alloy includes at least 0.40 wt. % Fe. In yet another embodiment, a new aluminum casting alloy includes at least 0.45 wt. % Fe. In another embodiment, a new aluminum casting alloy includes at least 0.50 wt. % Fe. In one embodiment, a new aluminum casting alloy includes not greater than 0.75 wt. % Fe. In another embodiment, a new aluminum casting alloy includes not greater than 0.70 wt. % Fe. In yet another embodiment, a new aluminum casting alloy includes not greater than 0.65 wt. % Fe.

As noted above, the new alminum casting alloys may optionally contain from 0.07 to 0.20 wt. % of X, where X is selected from the group consisting of Mg, Mo, Zr, and combinations thereof. The group X elements may, for instance, provide enhanced strength. In one embodiment, a new aluminum casdting alloy includes from 0.07 to 0.18 wt. % of X. In one embodiment, a new aluminum casdting alloy includes from 0.07 to 0.15 wt. % of X. In one embodiment, a new aluminum casdting alloy includes from 0.07 to 0.12 wt. % of X. In one embodiment, a new aluminum casdting alloy includes from 0.07 to 0.10 wt. % of X.

In other embodiments, the new aluminum casting alloys are substantially free of all of Mg, Mo, and Zr, having less than 0.07 wt. % of each of Mg, Mo, and Zr. In another embodiment, the new aluminum casting alloys include not greater than 0.05 wt. % of each of Mg, Mo, and Zr. In yet another embodiment, the new aluminum casting alloys include not greater than 0.04 wt. % of each of Mg, Mo, and Zr. In yet another embodiment, the new aluminum casting alloys include not greater than 0.03 wt. % of each of Mg, Mo, and Zr. In yet another embodiment, the new aluminum casting alloys include not greater than 0.02 wt. % of each of Mg, Mo, and Zr.

As noted above, the new aluminuim casting alloys may optionally contain stronium (Sr), such as 100-500 ppm Sr. In other embodiments, the new aluminum casting alloys are substantially free of strontium, having less than 100 ppm Sr. In one embodiment, a new aluminum casting alloy includes not greater than 50 ppm Sr. In another embodiment, a new aluminum casting alloy includes not greater than 25 ppm Sr. In yet another embodiment, a new aluminum casting alloy includes not greater than 10 ppm Sr.

The balance of the new aluminum casting alloys is generally aluminum and unavoiable impurities. In this regard, the new aluminum casting alloys are generally substantially free of all of copper (Cu), manganese (Mn), titanium (Ti), chromium (Cr), nickel (Ni), zinc (Zn), and vanadium (V).

As used herein, “substantially free of copper” means that the new aluminum alloys contain less than 0.10 wt. % Cu. In one embodiment, a new aluminum alloy contains not greater than 0.05 wt. % Cu. In another embodiment, a new aluminum alloy contains not greater than 0.03 wt. % Cu. In yet another embodiment, a new aluminum alloy contains not greater than 0.01 wt. % Cu.

As used herein, “substantially free of manganese” means that the new aluminum alloys contain less than 0.05 wt. % Mn. In one embodiment, a new aluminum alloy contains not greater than 0.04 wt. % Mn. In another embodiment, a new aluminum alloy contains not greater than 0.03 wt. % Mn. In yet another embodiment, a new aluminum alloy contains not greater than 0.02 wt. % Mn.

As used herein, “substantially free of zinc” means that the new aluminum alloys contain less than 0.10 wt. % Zn. In one embodiment, a new aluminum alloy contains not greater than 0.05 wt. % Zn. In another embodiment, a new aluminum alloy contains not greater than 0.03 wt. % Zn. In yet another embodiment, a new aluminum alloy contains not greater than 0.01 wt. % Zn.

As used herein, when referring to any of titanium, chromium, nickel and vanadium, “substantially free” means that the new aluminum alloy contains not greater than 0.04 wt. % of any of those elements, i.e., the new aluminum alloy contains not greater than 0.04 wt. % of each of Ti, Cr, Ni, and V. In one embodiment, a new aluminum alloy contains not greater than 0.03 wt. % of each of Ti, Cr, Ni, and V. In another embodiment, a new aluminum alloy contains not greater than 0.02 wt. % of each of Ti, Cr, Ni, and V. In one embodiment, the cummulative amounts of Ti, Cr, Ni, and V do not exceed 0.10 wt. %. In another embodiment, the cummulative amounts of Ti, Cr, Ni, and V do not exceed 0.08 wt. %. In yet another embodiment, the the cummulative amounts of Ti, Cr, Ni, and V do not exceed 0.06 wt. %.

ii. Processing

The new aluminum casting alloys may be cast using any suitable casting method. In one embodiment, the new aluminum casting alloys are shape cast using high presssure die casting (HPDC). In another embodiment, a new aluminum casting alloy is shape cast into a shape cast product (e.g., a complex shape cast product). In one embodiment, the shape cast product is a heat sink. In one embodiment, the shape cast product is in the form of an antenna. In one embodiment, the shape cast product has a wall thickness of from 1.5 to 5.0 mm. In one embodiment, the shape cast product has a height of from 50 to 100 mm. The new aluminum casting alloys may be provided in any appopriate temper, including the as-cast temper.

iii. Properties

As noted above, the new aluminum casting alloys may realize an improved combination of properties, such as an improved combination of at least two of strength, thermal conductivity, corrosion resistance, fluidity, and die soldering resistance. Mechanical properties may be measured in accordance with ASTM E8 and B557 (e.g., when directionally solidified). Die soldering resistance may be determined by casting the alloy.

In one embodiment, a new aluminum casting alloy realizes a tensile yield strength of at least 65 MPa. In one embodiment, a new aluminum casting alloy realizes an elongation of at least 2%.

In one embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 160 W/m/° C. at a temperature of 25° C. Thermal conductivity may be measured using equation 1 of ASTM equation 1 of ASTM E1461 using thermal diffusivity results obtained per ASTM E1461-13, specific heat capacity results obtained per ASTM E1269-11 (2018) and density results per ASTM B311-17. In another embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 170 W/m/° C. at a temperature of 25° C. In yet another embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 175 W/m/° C. at a temperature of 25° C. In another embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 180 W/m/° C. at a temperature of 25° C. In yet another embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 185 W/m/° C. at a temperature of 25° C. In another embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 190 W/m/° C. at a temperature of 25° C. In yet another embodiment, a new aluminum casting alloy realizes a thermal conductivity of at least 195 W/m/° C., or higher, at a temperature of 25° C.

In one embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 38% IACS (International Annealed Copper Standard). In another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 39% IACS. In yet another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 40% IACS. In another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 41% IACS. In yet another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 42% IACS. In another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 43% IACS. In yet another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 44% IACS. In another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 45% IACS. In yet another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 46% IACS. In another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 47% IACS. In yet another embodiment, a new aluminum casting alloy realizes an electical conductivity of at least 48% IACS, or more.

In one embodiment, a new aluminum casting alloy is corrosion resistant. As used herein, “corrosion resistant” means the new aluminum casting alloy realizes the same or better corrosion resistance as compared to conventional alloy A356 when tested in accordance with ASTM G110.

In one embodiment, a new aluminum casting alloy has good fluidity. As used herein, “good fluidity” means the new aluminum casting alloy realizes the same or better fluidity as compared to conventional alloy A365 under similar high-pressure die casting conditions.

In one embodiment, a new aluminum casting alloy is die soldering resistant wherein the as-cast aluminum alloy product is removed from the die without damage to the cast product and/or without sticking to the die. Die soldering can occur during high pressure die casting wherein molten aluminum solders to the die surface. In some embodiments, the new aluminum casting alloys described herein may be cast without being soldered to the die.

DETAILED DESCRIPTION EXAMPLE 1

Six aluminum alloys were directionally solified. The compositons of the alloys are shown in Table 1, below.

TABLE 1 Alloy Compositions Alloy* Si (wt. %) Fe (wt. %) Sr (ppm) 1 10.7 0.52 170 2 10.5 0.51 — 3 8.6 0.51 — 4 6.7 0.52 — 5 5.0 0.55 20 6 3.1 0.55 — *The balance of the alloys was aluminum and impurities. All alloys contained less than 0.01 wt. % Cu. All alloys contained less than 0.02 wt. % Mn. All alloys contained less than 0.03 wt. % Mg. All alloys contains less than 0.01 wt. % of each of Cr, Ni, Zn, Ti, and Zr. All alloys contained less than 0.02 wt. % of V. The remaining impurities were all less than 0.01 wt. % each.

The thermal conducity of the alloys was measured at various temperatures, the results of which are shown in Table 2 below. Thermal conductivity may be measured using equation 1 of ASTM E1461 using thermal diffusivity results obtained per ASTM E1461-13, specific heat capacity results obtained per ASTM E1269-11 (2018) and density results per ASTM B311-17.

TABLE 2 Thermal Conductivity Results Temp. Thermal Conductivity (W/m/° C.) (° C.) Alloy 6 Alloy 5 Alloy 4 Alloy 3 Alloy 2 Alloy 1 25 203 197 196 191 192 190 100 200 195 193 190 191 187 200 201 197 193 190 190 195 300 203 198 191 189 186 180 400 204 201 198 192 185 181 500 221 213 204 202 203 195

As shown, the alloys realize high thermal conductivity. Further alloys 1-4 are expected to realize good fluidity due to their silicon content. Alloy 1-2 are expected to have excellent fluidity.

While various embodiments of the present disclosure have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present disclosure. 

What is claimed is:
 1. An aluminum casting alloy comprising: from 6.0 to 11.5 wt. % Si; from 0.30 to 0.80 wt. % Fe; optionally from 0.07 to 0.20 wt. % of X, wherein Xis selected from the group consisting of Mg, Mo, Zr, and combinations thereof; and optionally 100-500 ppm Sr; the balance being aluminum and unavoidable impurities.
 2. The aluminum casting alloy of claim 1, comprising at least 7.0 wt. % Si, or at least 8.0 wt. % Si, or at least 9.0 wt. % Si, or at least 9.5 wt. % Si.
 3. The aluminum casting alloy of claim 1, comprising not greater than 11.0 wt. % Si, or not greater than 10.5 wt. % Si.
 4. The aluminum casting alloy of claim 1, comprising at least 0.35 wt. % Fe, or at least 0.40 wt. % Fe, or at least 0.45 wt. % Fe, or at least 0.50 wt. % Fe.
 5. The aluminum casting alloy of claim 1, comprising not greater than 0.75 wt. % Fe, or not greater than 0.70 wt. % Fe, or not greater than 0.65 wt. % Fe.
 6. The aluminum casting alloy of claim 1, wherein the aluminum casting alloy includes X.
 7. The aluminum casting alloy of claim 6, comprising from 0.07 to 0.18 wt. % of X, or from 0.07 to 0.15 wt. % of X, or from 0.07 to 0.12 wt. % of X, or from 0.07 to 0.10 wt. % of X.
 8. The aluminum casting alloy of claim 1, wherein the aluminum casting alloy is substantially free of all of Mg, Mo, and Zr, having less than 0.07 wt. % of each of Mg, Mo, and Zr.
 9. The aluminum casting alloy of claim 8, comprising not greater than 0.05 wt. % of each of Mg, Mo, and Zr, or not greater than 0.04 wt. % of each of Mg, Mo, and Zr, or not greater than 0.03 wt. % of each of Mg, Mo, and Zr, or not greater than 0.02 wt. % of each of Mg, Mo, and Zr.
 10. The aluminum casting alloy of claim 1, wherein the aluminum casting alloy includes Sr.
 11. The aluminum casting alloy of claim 1, wherein the aluminum casting alloy includes less than 100 ppm Sr, or not greater than 50 ppm Sr, or not greater than 25 ppm Sr, or not greater than 10 ppm Sr.
 12. The aluminum casting alloy of claim 1, wherein the aluminum casting alloys is substantially free of copper, manganese, zinc, titnaium, chromium, nickel, and vanadium.
 13. The aluminum casting alloy of claim 12, comprising less than 0.10 wt. % Cu, or not greater than 0.05 wt. % Cu, or not greater than 0.03 wt. % Cu, or not greater than 0.01 wt. % Cu.
 14. The aluminum casting alloy of claim 12, comprising not greater than 0.04 wt. % Mn, or not greater than 0.03 wt. % Mn, or not greater than 0.02 wt. % Mn.
 15. The aluminum casting alloy of claim 12, comprising less than 0.10 wt. % Zn, or not greater than 0.05 wt. % Zn, or not greater than 0.03 wt. % Zn, or not greater than 0.01 wt. % Zn.
 16. The aluminum casting alloy of claim 12, comprising not greater than 0.04 wt. % of each of Ti, Cr, Ni, and V, or not greater than 0.03 wt. % of each of Ti, Cr, Ni, and V, or not greater than 0.02 wt. % of each of Ti, Cr, Ni, and V.
 17. The aluminum casting alloy of claim 16, wherein the cummulative amounts of Ti, Cr, Ni, and V do not exceed 0.10 wt. %, or wherein the cummulative amounts of Ti, Cr, Ni, and V do not exceed 0.08 wt. %, or wherein the cummulative amounts of Ti, Cr, Ni, and V do not exceed 0.06 wt. %.
 18. A high-pressure die cast product made from the aluminum casting alloy of claim
 1. 19. The high-pressure die cast product of claim 18, wherein the product realizes a tensile yield strength of at least 65 MPa and an elongation of at least 2%.
 20. The high-pressure die cast product of claim 18, wherein the product realizes a thermal conductivity of at least 160 W/m/° C. at a temperature of 25° C., or at least 170 W/m/° C. at a temperature of 25° C., or at least 175 W/m/° C. at a temperature of 25° C., or at least 180 W/m/° C. at a temperature of 25° C., or at least 185 W/m/° C. at a temperature of 25° C., or at least 190 W/m/° C. at a temperature of 25° C., or at least 195 W/m/° C., or higher, at a temperature of 25° C. 